Noninvasive videomicroscopic monitoring of rat small-bowel rejection

Successful small-bowel transplantation requires an early diagnosis of graft rejection. To date, little is known about macroscopic mucosal alterations during rejection. In the present study, these changes were analyzed in detail. Videomicroscopic monitoring of an enterostoma was performed after allogeneic heterotopic small-bowel transplantation in the rat (BN to LEW). Up to postoperative day (POD) 3 a mucosal edema was noticed (stage I of videomicroscopical alterations). The earliest changes related to rejection appeared on POD 6. The mucosa of the grafted intestine developed patchy paleness and interruptions in mucosal architecture. Crypts were slightly widened and their color turned to dark red (stage IIa). Progressively, these alterations spread over the mucosa on POD 7 (stage IIb). On POD 9, the mucosa appeared pale, villi were shortened, and crypts appeared wide and rounded. The mucosal surface was coated with fibrinous membranes (stage III). The videomicroscopic findings were closely related to the histological grading of rejection. We regard this technique of mucosal monitoring a simple and noninvasive method of detecting allograft rejection.